EF Core Migrations Troubleshooting Guide — Design Package, Tooling Versions & Multi‑Project Setups
If you work with Entity Framework Core long enough, you’ll eventually hit the “migrations wall”:
“The contextual keyword 'var'…“? No.
“Cannot drop database because it is currently in use”? Sometimes.
But more often it’s one of these three classics:
“Your startup project doesn’t reference Microsoft.EntityFrameworkCore.Design”
“The Entity Framework tools version 9.0.5 is older than runtime 10.0.0”
“Your target project TechNotes doesn’t match your migrations assembly TechNotes.Infrastructure”
The good news: these errors are 100% normal in real-world, multi-project solutions—and they’re also 100% fixable once you understand what EF Core is trying to tell you.
This post is a copy‑paste‑ready troubleshooting guide you can keep open in your terminal while you work.
Design‑Time Package Missin…
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